This online section begins by looking at how human vision operates in order to understand our eyes as the primary tool of photography. Not only do our eyes work in particular ways to focus and frame our visual world, but all optical devices (cameras, scanners, etc.) depend upon or extend our visual acuity and limitations. An understanding of how you use your eyes, and their capabilities, helps you to make choices with other technologies. This section describes the eye/brain visual system, but also looks at how visual aids, such as contact lenses, binoculars and telescopes, extend our biological tools.
In the Reframing Photography book, the camera as viewer describes how cameras obscura, camera viewfinders, viewing systems and lenses enable us to see. Camera as recorder describes different camera formats that record visual data, from small, medium and large digital- and film-based cameras, to instant and cell phone cameras, photocopiers and scanners. This section describes options, such as size of the film or sensor, storage ability, and processing capabilities, how to operate each camera body and how to control components such as aperture and shutter.